As a solid-state image pickup device such as a charge coupled device (CCD) image sensor and a complementary metal oxide semiconductor (CMOS) image sensor, a single-chip CCD color solid-state image pickup device that performs color separation with use of color filters is known. The single-chip CCD color solid-state image pickup device is configured in such a manner that a color filter of any one of a plurality of colors (for example, R, G, and B) is provided for each pixel, and a photoelectric conversion layer is provided in common, for example. Therefore, each pixel receives light of only one color. Accordingly, light usage efficiency is low and the resolution of color images is also low. In addition, since each color light of R, G, and B is detected at positions different from one another in a plane, false color is easily generated. Therefore, optical low-pass filters are necessary. Further, the low-pass filters may cause optical loss.
In contrast, a solid-state image pickup device in which a plurality of photoelectric conversion layers absorbing colors different from one another (for example, R, G, and B) are stacked in one pixel, and signals of three colors are obtained from one pixel has been proposed (for example, PTL 1). In the solid-state image pickup device in PTL 1, each of the photoelectric conversion layers is formed of semiconductor nanoparticles covered with an insulating film, and band gap control with use of quantum confinement effect of the semiconductor nanoparticles is performed. Such a stacked-type solid-state image pickup device provides high color separation performance, high quantum efficiency, and high sensitivity.
Incidentally, a technology relating thereto, a solid-state image pickup device provided with a photoelectric conversion layer in which quantum dots of narrow gap semiconductor are disposed in a conductive film has been also proposed (for example, PTL 2). Further, in PTL 3, a color sensor including photoelectronic material in which semiconductor ultrafine particles are disposed in a transparent medium has been proposed.